Final answer:
Concept musicals, exemplified by 'Chicago', 'A Chorus Line', and 'Company', revolutionized the theatre industry with their character-driven narratives that focus on contemporary themes and social commentary.
Step-by-step explanation:
The genre described in the question, which usually features a libretto, onstage musicians, is character-driven, and revolves around a central theme without being restricted by a driving plotline, is known as a concept musical.
Shows like Chicago, A Chorus Line, and Company have each played a role in putting concept musicals on the map. They emerged at a time of cultural and social change in the United States, with audiences craving new forms of storytelling that reflected contemporary issues. These musicals often challenged social norms and introduced diverse characters and unconventional storytelling, which has continued to impact theatre production up to today's Broadway!